ALTON--Ardyth. The Juilliard School mourns the passing of Ardyth Alton, a member of the School's college and precollege cello faculties since 1968. With expertise, artistry and a gentle manner, Ardyth brought the joy of musicmaking and the glories of the violoncello to generations of young musicians. We will deeply miss her elegant and caring persona. Our condolences are extended to her entire family. A concert in her memory with her daughter, cellist Ann Alton, and others performing takes place in Juilliard's Paul Hall (144 W. 66th St.) on Saturday, February 23 at 6pm. Call 212-799-5000 x241 for information. Bruce Kovner, Chairman Joseph W. Polisi, President